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Finding the Fourth Proportional to 81.74, 121.95 and 77.87

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Solution

The fourth proportional to 81.74, 121.95 and 77.87 is: 116.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.74 : 121.95 = 77.87 : x
  2. Step 2: Convert to fraction form
    81.74/121.95 = 77.87/x
  3. Step 3: Cross multiply
    81.74x = 121.95 × 77.87
  4. Step 4: Simplify right side
    81.74x = 9,496.55
  5. Step 5: Solve for x
    x = 9,496.55/81.74
  6. Step 6: Final answer
    x = 116.18

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.